Technical Field
The present invention relates to a semiconductor device and a method of controlling thereof.
Background Art
A booster circuit or a level shifter (converter) is generally used for a conventional drive circuit configured to control the driving of a liquid crystal device (see, for example, Japanese Laid-Open Patent Publication 1999-014961). Also, a high voltage transistor is generally used as a switching element for a booster circuit which performs a boost operation where the reference voltage is boosted by a factor of 3 so that the switching element for the boost operation does not break.
Also, when a high voltage transistor is used for a booster circuit, since the on-resistance of the high voltage transistor is relatively great while the drain current is relative small, the boost efficiency of the booster circuit and the consequent display quality of the liquid crystal display device are reduced. In order to achieve a good display quality of the liquid crystal display device (by increasing the boost efficiency), the size of the high voltage transistor is increased so as to reduce its on-resistance and to increase the drain current.